Which statement best describes slow-twitch muscle fibers?

Which statement best describes slow-twitch muscle fibers?

• A. They fatigue quickly
• B. They contract slowly and are resistant to fatigue
• C. They produce high force quickly
• D. They have quick speed of contraction

Answer: (B)

Slow-twitch muscle fibers are built for endurance: they contract slowly, rely on aerobic metabolism, and have a rich supply of mitochondria and capillaries with high myoglobin content. This setup lets them work for long periods without fatiguing, producing a smaller amount of force but sustaining it. That’s why the description “contract slowly and are resistant to fatigue” fits best. By contrast, fast-twitch fibers are the ones that contract quickly, produce higher force, and fatigue more rapidly, so statements about rapid contraction or high force point to them.

Slow-twitch muscle fibers are built for endurance: they contract slowly, rely on aerobic metabolism, and have a rich supply of mitochondria and capillaries with high myoglobin content. This setup lets them work for long periods without fatiguing, producing a smaller amount of force but sustaining it. That’s why the description “contract slowly and are resistant to fatigue” fits best. By contrast, fast-twitch fibers are the ones that contract quickly, produce higher force, and fatigue more rapidly, so statements about rapid contraction or high force point to them.